[release/11.0.1xx-preview4] [dotnet] Fix R2R --instruction-set computation for iOS/tvOS device builds

[rolfbjarne]

Summary

_ComputeInstructionSetForCrossgen2 was passing $(TargetFramework) (the short form like net11.0-ios) as TargetFrameworkMoniker. The base task calls TargetFramework.Parse, which only handles the long comma-delimited form (.NETCoreApp,Version=v11.0,Profile=ios); the short form silently parses to an empty TargetFramework whose Platform getter falls through to ApplePlatform.MacOSX.

For an ios-arm64 build the platform was therefore reported as macOS, so ComputeMinimumInstructionSet routed to ComputeMacInstructionSet, which returns apple-m1 for any arm64 RID. crossgen2 was then invoked with --instruction-set:apple-m1 even on iOS device builds.

Impact

apple-m1 requires ARMv8.5 features. Pre-A14 iOS devices (iPhone XR/A12, iPhone 11/A13, etc.) do not implement them, so the runtime rejects the R2R image at load time and falls back to the interpreter — defeating R2R on a wide range of supported devices and visibly regressing cold-start.

This was originally observed in MAUI/M365 startup measurements where CoreCLR Release on iPhone XR was ~2× slower than Mono Release; profiling pointed at interpreter fallback, and the binlog showed --instruction-set:apple-m1 on the crossgen2 line plus the misleading Computed instruction set 'apple-m1' for macOS 15.0 log message for an iOS build.

Fix

The other call sites in the same file already use $(_ComputedTargetFrameworkMoniker) (the long form expanded by the shared targets). Align this one with them — one-line change.

---

Co-authored-by: Milos Kotlar kotlarmilos@users.noreply.github.com
Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com
Co-authored-by: Rolf Bjarne Kvinge rokvin@microsoft.com

Backport of #25337.

[Copilot]

Pull request overview

Fixes ReadyToRun (crossgen2) instruction-set selection for iOS/tvOS device builds by ensuring _ComputeInstructionSetForCrossgen2 passes a long TargetFrameworkMoniker (with the correct Apple platform profile) to the ComputeInstructionSet task, preventing iOS/tvOS arm64 builds from being misdetected as macOS and incorrectly using apple-m1.

Changes:

• Update _ComputeInstructionSetForCrossgen2 to pass $(_ComputedTargetFrameworkMoniker) instead of $(TargetFramework) to ComputeInstructionSet.
• Refresh AppSizeTest expected size baselines across iOS/tvOS/macOS/MacCatalyst configurations to match new build outputs.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
dotnet/targets/Microsoft.Sdk.R2R.targets	Fix ComputeInstructionSet input to use the long computed TFM so iOS/tvOS device builds compute the correct instruction set.
tests/dotnet/UnitTests/expected/TVOS-NativeAOT-size.txt	Update expected tvOS NativeAOT bundle size baseline.
tests/dotnet/UnitTests/expected/TVOS-MonoVM-size.txt	Update expected tvOS MonoVM bundle size baseline.
tests/dotnet/UnitTests/expected/TVOS-MonoVM-interpreter-size.txt	Update expected tvOS MonoVM (interpreter) bundle size baseline.
tests/dotnet/UnitTests/expected/TVOS-CoreCLR-R2R-size.txt	Update expected tvOS CoreCLR R2R bundle size baseline.
tests/dotnet/UnitTests/expected/TVOS-CoreCLR-Interpreter-size.txt	Update expected tvOS CoreCLR interpreter bundle size baseline.
tests/dotnet/UnitTests/expected/MacOSX-NativeAOT-size.txt	Update expected macOS NativeAOT bundle size baseline.
tests/dotnet/UnitTests/expected/MacOSX-CoreCLR-R2R-size.txt	Update expected macOS CoreCLR R2R bundle size baseline.
tests/dotnet/UnitTests/expected/MacOSX-CoreCLR-Interpreter-size.txt	Update expected macOS CoreCLR interpreter bundle size baseline.
tests/dotnet/UnitTests/expected/MacCatalyst-NativeAOT-size.txt	Update expected Mac Catalyst NativeAOT bundle size baseline.
tests/dotnet/UnitTests/expected/MacCatalyst-MonoVM-size.txt	Update expected Mac Catalyst MonoVM bundle size baseline.
tests/dotnet/UnitTests/expected/MacCatalyst-MonoVM-interpreter-size.txt	Update expected Mac Catalyst MonoVM (interpreter) bundle size baseline.
tests/dotnet/UnitTests/expected/MacCatalyst-CoreCLR-R2R-size.txt	Update expected Mac Catalyst CoreCLR R2R bundle size baseline.
tests/dotnet/UnitTests/expected/MacCatalyst-CoreCLR-Interpreter-size.txt	Update expected Mac Catalyst CoreCLR interpreter bundle size baseline.
tests/dotnet/UnitTests/expected/iOS-NativeAOT-size.txt	Update expected iOS NativeAOT bundle size baseline.
tests/dotnet/UnitTests/expected/iOS-MonoVM-size.txt	Update expected iOS MonoVM bundle size baseline.
tests/dotnet/UnitTests/expected/iOS-MonoVM-interpreter-size.txt	Update expected iOS MonoVM (interpreter) bundle size baseline.
tests/dotnet/UnitTests/expected/iOS-CoreCLR-R2R-size.txt	Update expected iOS CoreCLR R2R bundle size baseline.
tests/dotnet/UnitTests/expected/iOS-CoreCLR-Interpreter-size.txt	Update expected iOS CoreCLR interpreter bundle size baseline.

[rolfbjarne]

Closing, too late to get into P4 at this point.